The present invention relates to testing data packet transceivers, and in particular, to testing data packet signal transceiver sensitivity.
Many of today's electronic devices use wireless technologies for both connectivity and communications purposes. Because wireless devices transmit and receive electromagnetic energy, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless technologies must adhere to various wireless technology standard specifications.
When deciding such wireless devices, engineers take extra care to ensure that such devices will meet or exceed each of their included wireless technology prescribed standard-based specifications. Furthermore, when these devices are later being manufactured in quantity, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless technology standard-based specifications.
For testing these devices following their manufacture and assembly, current wireless device test systems employ a subsystem for analyzing signals received from each device. Such subsystems typically include at least a vector signal generator (VSG) for providing the source signals to be transmitted to the device under test, and a vector signal analyzer (VSA) for analyzing signals produced by the device under test. The production of test signals by the VSG and signal analysis performed by the VSA are generally programmable so as to allow each to be used for testing a variety of devices for adherence to a variety of wireless technology standards with differing frequency ranges, bandwidths and signal modulation characteristics.
As part of the manufacturing of wireless communication devices, one significant component of production cost is costs associated with manufacturing tests. Typically, there is a direct correlation between the cost of test and the time required to perform the test. Thus, innovations that can shorten test time without compromising test accuracy or increasing Equipment costs (e.g., increasing costs due to increasing sophistication of necessary test equipment, or testers) are important and can provide significant costs savings, particularly in view of the large numbers of such devices being manufactured and tested.
A common receiver (RX) test for such DUTs is determining signal sensitivity as a function of power level, e.g., the signal envelope power of the data packet signal, where some standard prescribed upper limit on packet error rate (PER) occurs (e.g., PER=(T−A)/T, where T=number of test data packets, and A=number of Acknowledgement data packets). For example, one sensitivity point can be defined as the power level where no more than 10% of the detected data packets are received incorrectly, i.e., where the packet data and appended check sum agree.
To determine such a sensitivity point, a sufficient number of data packets are required to be sent to the DUT by the tester to ensure that at least 90% of the data packets sent are correctly received. This would then establish the desired sensitivity point. However, if the test yields a PER different than 10%, it may be difficult to derive useful information about the sensitivity of the DUT. For example, if the PER is 0%, i.e., all data packets have been received correctly, or 100%, i.e., no data packets have been received correctly, very little information can be derived from such a PER, other than a conclusion that the DUT is better or worse than the tested level.
Accordingly, it would be desirable to have a technique for testing sensitivity of a DUT such that PER can be tested accurately in a time efficient manner.